available methods to measure vitamin b12 - The IIOAB Journal

The IIOAB Journal 

ISSN: 0976-3104 

REVIEW: MEDICAL LAB TECHNOLOGY 

MEASUREMENT OF VITAMIN B 12 CONCENTRATION: A REVIEW ON 

AVAILABLE METHODS 

Ola Karmi*, Ashraf Zayed, Suheir Baraghethi, Muhammad Qadi, Rasha Ghanem 

Department of Medical Laboratory Sciences, Faculty of Health Professions, Al-Quds University, (Master Program in 

Hematology and Microbiology), Jerusalem, PALESTINE 

Received on: 9 th -July-2010; Revised on: 22 nd -Nov-2010; Accepted on: 30 th -Nov-2010; Published on: 10 th -Jan-2011 

* Corresponding author: Email: olakarmi@yahoo.com Tel: +972-598-242829 

ABSTRACT 

_____________________________________________________ 

Vitamin B12 is a water-soluble vitamin. It is one of the eight vitamins of vitamin B complex, needed for 

blood and cell maturation. It helps maintain healthy nerve cells and red blood cells, and it is needed in 

DNA replication. Its deficiency may cause megaloblastic anemia (amidst others health issues). For 

these and many similar reasons, it sometimes becomes necessary to measure its concentration. This 

article has carefully reviewed the different methods used for measuring vitamin B12 concentration, and 

the unique principles involved. The principles, basically, depend on the molecular structure of Vitamin 

B12 and its reactions with other substances. The methods include microbiological assay and 

spectrophotometric methods – these are old methods: they were the first available methods, but they 

are still in use for reference purposes. Another method is electroluminescent (ECL) which involves 

highly reactive materials. However, inductive-coupled plasma-mass spectrometry (ICP-MS) is a very 

important method, which is used routinely, even in many research. On the other hand, atomic 

absorption spectroscopy depends on measuring the amount of energy involved in the reaction; while 

radioimmunoassay (RIA) is a highly sensitive immunoassay technique. In addition, there are different 

techniques for separating and preparing samples to be used in the various measurement methods. 

High-performance liquid chromatography (HPLC) is used for non-validate analyst, while capillaryelectrophoresis 

(CE) that have high resolving power than traditional electrophoresis, which when they 

are coupled with certain detectors they afford us another principle for measuring this vitamin. 

Choosing the best method for measuring vitamin B12 concentration depends on many factors – 

including the type of sample, purpose of the test, necessity of pre-processing, time limitations, cost, 

sensitivity, specificity. 

_____________________________________________________ 

Keywords: Electroluminescence; Inductive-Coupled Plasma-Mass Spectrometry; microbiological assay; radioimmunoassay; 

capillary-electrophoresis; vitamin B12 concentration 

[I] INTRODUCTION 

Vitamin B12 is a water-soluble vitamin. It is one of the “B 

complex vitamins,” which play roles in red blood cell formation, 

nerve cell maintenance, and methyl donation in DNA synthesis. 

Deficiency of vitamin B12 affects immunologic and hematologic 

parameter in the body [1]. 

Human’s source of vitamin B12 is of animal origin. It was in 

1948 that vitamin B12 was first isolated from liver juice, and it 

was used in treating pernicious anemia [2]. Vitamin B12 consists 

of corrin ring (synthesized by bacteria) and cobalt ion; and this 

cobalt-corrin ring complex gives vitamin B12 its red colouration. 

Different forms of vitamin B12 are similar in the cobalt central 

ion, the four parts of the corrin ring and a dimethylbenzimidazole 

group, but differ in the sixth site which may contain cyano group 

(CN), hydroxyl group (OH), methyl group (CH3) and/or 5'- 

deoxyadenosyl group (C-CO) [3,4]. 

There are several methods to assay and calculate vitamin B12. 

Some of these methods are used in medical field, and some 

others in pharmacological studies/investigations. This review 

©IIOAB-India OPEN ACCESS Vol. 2; Issue 2; 2011: 23-32 

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focuses on some of the weaknesses and strengths of these 

methods, and aims to identify the best method for measuring the 

concentration of vitamin B12. 

[II] HISTORICAL TECHNIQUES 

2.1. Microbiological and spectrophotometric 

methods 

Microbiological method is one of the oldest methods for 

measuring the concentration of vitamin B12. Information 

regarding this method has been extensively documented [5]. 

Ross (1950) was the first scientist to describe microbiological 

method using Euglena gracilis var-bacillaris as test organism. 

Thereafter there was introduction of Z strain of Euglena gracilis 

so as to shorten the growth period required for the test to as low 

a five days [6]. Further experiments on measurement of vitamin 

B12 focused on either changing microorganism test or 

developing test techniques, such as adding heating step or some 

substances to the test procedures for converting vitamin B12 to 

the active free form [6]. Also, several microorganisms were 

proposed for the microbiological assay. These methods include 

Euglena gracilis tube method, filter paper disc method (FPD), 

Escherichia coli tube method, plate method, Lactobacillus 

leishmanii tube method, bioautographic method, and 

Ochromonas malhamensis tube method [7]. However, Euglena 

gracilis and Lactobacillus leishmanii are the most commonly 

used methods [5,7,8]. 

Davis et al [6] described a fully automated method for the 

microbiological measurement of vitamin B12 using 

chloramphenicol-resistance strain of Lactobacillus leishmannii 

as test organism. Chloramphenicol eliminates the need for 

sterilization. Using this method, results could be available within 

24 hours. This automated method solved the challenge of how to 

dissociate vitamin B12 from its protein carrier. This was possible 

by treating the sample with a solution containing glutamic/malic 

acid [6]. 

Automated microbiological method was designed to use 

Mecolab M which is a multi-instrument that provides facilities 

for sample dilution, reagent addition and mixing, as well as 

measurement and digital estimation of bacterial growth. It 

consists of sample preparation unit, autocolorimeter, A/D 

converter and calculator [6]. 

Years after, scientists have tried to develop a microbiological 

method by using microtiter plates. They used chloramphenicol 

resistance strain of lactobacillus casei on serum and red blood 

cell folates. Then they compared the results with traditional 

microbiological method. They obtained better results with better 

intra-assay precision for both serum and red cells (CV% of


[III] PRESENT ACTUAL TECHNIQUES 

3.1. Electroluminescence (ECL) 

Electroluminescence (ECL) is a process in which reaction of 

highly reactive molecules are generated from stable state 

electrochemically by an electron flow cell forming highly reacted 

species on a surface of a platenium electrode producing light 

[21]. This method uses ruthenium (II)-tris (bipyridyl) [Ru (bpy) 3 

] 2+ complex and triproplamine (TPA) and react them with each 

other to emit light. The applied voltage creates an electrical field 

that causes the reaction of all materials. Tripropylamine (TPA) 

oxidized at the surface of the electrode, releases an electron and 

forms an intermediate which may further react by releasing a 

proton. In turn the ruthenium complex releases an electron at the 

surface of the electrode forming an oxidized form of Ru(bpy) 3 

3+ 

cation, which is the second reaction component for the 

chemiluminescent reaction. Then this cation will reduce and 

form Ru(bpy) 3 2+ and an exited state via energy transfer which is 

unstable and decays with emission of photon at 620 nm to its 

original state [21, 22]. 

ISSN: 0976-3104 

The florescence emitted by Ru(bpy) 3 

2 + is detected by standard 

photomultiplier, and the results are expressed as ECL intensity, 

which is the measurement of the whole luminescence emitted 

from the sample [23]. This method employs various test 

principles (such as competitive principle, sandwich and bridging) 

for the measurement [22]. The most important one in measuring 

vitamin B12 concentration is the competitive principle. The 

competitive principle is applied to low molecular weight 

molecules. It uses antibodies (intrinsic factor) for vitamin B12 

labeled with ruthenium complex. These antibodies are incubated 

with the sample, then biotinylated vitamin B12 and streptavidin 

which is coated with paramagnetic miroparticles are added to the 

mixture. The free binding sites of the labeled antibody become 

occupied with the formation of an antigen-hapten complex. Then 

the entire complex is bonded to biotin and streptavidin. After 

incubation the reaction mixture is transported into the measuring 

cell where the immune complexes are magnetically entrapped on 

the working electrode and the excess unbound reagent and 

sample are washed away. Then the reaction is stimulated 

electrically to produce light which is indirectly proportional to 

the amount of vitamin B12 that is measured [Figure–1] [22]. 

Fig: 1. Electroluminescence method, competitive principle for measuring vitamin B12. Step 1: Vitamin B12 from serum sample 

enters to the flow channel. Step 2: Vitamin B12 particles from the reagent are bonded to streptavidin-biotin to help in their attachment 

to the magnet part. Step 3: Intrinsic factor (which acts as antibodies) are bounded to ECL particles to enhance the reaction. Step 4: 

Vitamin B12 from the sample with the particles from the reagent bind to the intrinsic factor. Step 5: Only intrinsic factor that is bonded 

to the vitamin B12 labeled with Streptavidin-biotin particles is attached to the working electrode (by magnetic action) were the ECL 

reaction will take place and the signal will be measured. The free intrinsic factor with the ones that binds to the vitamin B12 from the 

sample will be washed away. 


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Test sample needed is serum, and the sample duration time is 27 

minutes, this test is very sensitive. It can even detect 22 pmol/L 

(30 pg/ml). It is also very precise (CV% is >10%), and very 

specific and cross reactivity rarely occurs. This test has high 

reproducibility, and can be processed easily. Machines used in 

this technique have extremely long life span with no 

maintenance costs. An example of such machines is Elecsys 

2010 and Cobas e 411. This technique is often used in 

pharmacological, industrial, clinical and chemical research [24]. 

3.2. Inductive-coupled plasma (ICP) - mass 

spectrometry (MS) (ICP-MS) 

One of the best methods for the determination of vitamin B12 

concentration is mass spectrometry (MS). This is because of its 

speed, sensitivity, easy (fully automated) and its vast possible 

application. It is one of the most important instruments for both 

routine and research applications. In contrast to what its name 

implies, MS actually measures mass to charge ratio and not just 

the mass. However, when the charge of all particles (ions) is the 

same, the mass spectrum plot is simplified to have only mass on 

the X- axis and the relative abundance on the Y-axis [25]. 

There are deferent types of MS but they all have three main 

components in common: an ionization source; mass analyzer; 

and detector. Ionization process occur in deferent ways in the 

different types of MS and that is what actually explains the 

differences between the deferent MS types. Ionization is an 

important step, and ensures the conversion of the the analyte of 

interest into gaseous phase ions. The first described ionization 

source is the electron ionization where the sample must be of low 

molecular weight, vaporizable and thermally stable. The 

analytes has to be vaporized and then ionized, and these limited 

the availability of such method for many biological samples and 

analytes so there was great need for developmental ionization 

sources [25, 26]. This lead to the development of electrospray 

ionization, atmospheric pressure chemical ionization and matrix 

assisted laser desorption ionization [25]. 

The first type of ionization source is Electrospray ionization 

(ESI). It depends on generation of electrons at atmospheric 

pressure by exposing the sample to different voltage depending 

on the boiling temperature of the liquid phase sample and the 

diameter of the inner capillary tube. Most machines with EIS 

also have additional or optional ionization technique which is 

Atmospheric Pressure Chemical Ionization or Inductively 

Coupled Plasma where ionization can also occurs at atmospheric 

pressure. But these differ from ESI in that sample travels through 

the different heating zones: when plasma torches it, it becomes 

dried, vaporized, atomized, and ionized. During this time, the 

sample is transformed from a liquid aerosol to solid particles, 

then into a gas, so that they are excited and they gain enough 

energy to release electrons from their orbits and generate ions. 

Like ESI and ICP, matrix assisted laser desorption ionization 

occurs in vacuum where laser irradiation pulsed is the source of 

ion generation [25, 26, 27]. 

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As Since the ionization sources can differ, there are also several 

types of mass analyzers. One of the simplest types is “Time of 

flight mass analyzer” where the velocity of the ions (which 

depends on the mass to charge ratio) leads to the separation of 

the ions in different speeds. When fixed potential force them 

toward the detector, the speed (time) of an ion in reaching the 

detectors is proportional to its mass to charge ratio – lower ratio 

is associated with higher velocity. The other type of the mass 

analyzer is the sector analyzer (magnetic or electric sectors are 

available). Here the ions are focused toward the detector after 

they have left the sector, through a split by applying a fixed 

accelerating potential. 

The widely used mass analyzer is the quadruple, especially with 

gas and liquid chromatography, since it is much smaller, easier, 

and cheaper than other analyzers. By placing a direct current 

(DC) field on one pair of rods and a radio frequency (RF) field 

on the opposite pair, ions of a selected mass are allowed to pass 

through the rods to the detector, while the others are ejected from 

the quadrupole. The other ions of different mass to-charge ratios 

will pass through the spaces between the rods and be ejected 

[Figure–2] [25, 27, 28]. 

To perform MS one needs to start with pure analyte to be able to 

use different MS types. So it is important to combined MS with 

other separation techniques such as capillary electrophoresis, 

HPLC, gas chromatography, and liquid chromatography, where 

Cobalamin in human urine and multivitamin tablet solutions can 

be converted into free cobalt ions in acid medium. The linearity 

of MS is over the cobalamin concentration range of 1.0 × 10−10 

g /mL− to 8.0 × 10−5 g /mL and the limit of detection is 0.05 ng/ 

mL for both ICP-MS and HPLC-MS. MS is often used in 

Pharmacology, industries, and in basic research, but not used in 

clinical field due to its high cost [29]. 

3.3. Atomic absorption spectroscopy 

Atomic absorption spectroscopy is an analytical chemistry 

technique used for determining concentration of particular metal 

element in a sample, and it is widely used in pharmaceutics. 

This technique can be used to analyze the concentration of over 

70 different metals in a solution [30]. The discovery of the 

Fraunhofer lines in the sun's spectrum in 1802 marked the 

beginning of the main phenomenon behind this technique. 

However, it was not until 1953 that Sir Alan W (Australian 

physicist) demonstrated the possibility of using atomic 

absorption for quantitative analysis [31]. Simply put, atomic 

absorption spectroscopy has to do with the measurement of the 

absorption of light by vaporized ground state atoms and then 

estimating the desired concentration from the absorption. 

Basically, the incident beam (of light) is attenuated by the 

absorption by atomic vapor according to Beer’s law [32]. 

A detector measures the wavelengths of light transmitted by the 

sample (called the “after wavelengths”), and compares them to 

the wavelengths, which was passed through the sample (the 


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“before wavelengths”). Moreover, a signal processing unit then 

processes the changes in wavelength, and gives the output for 

discrete wavelengths as peaks of energy absorption. Since, an 

atom is unique in its absorption pattern of energy at various 

wavelengths due to the unique configuration of electrons in its 

outer shell, the qualitative analysis of a pure sample can be 

achieved [32]. This, in fact, makes it reasonable for this method 

to measure the quantity of energy (in the form of photons of 

ISSN: 0976-3104 

light) absorbed by the sample. Using this technique, various 

metals in organic samples can be analyzed. The basic structure of 

the machine consists of 4 basic structural elements; a light source 

(hollow cathode lamp), an atomizer section for atomizing the 

sample (burner for flame, graphite furnace for electro thermal 

atomization), a monochromatic for selecting the analysis 

wavelength of the target element, and a detector for converting 

the light into an electrical signal [Figure–3] [33]. 

Fig: 2. Inductive-Coupled Plasma-Mass Spectrometry (ICP-MS). A. Mass Spectrometry: Shows the basic components of a typical 

mass spectrometry. All mass spectrometry shares three main components; an ionization source, mass analyzer, and detector. B. 

Inductive-Coupled Plasma: It serves as the ionization source in some particular types of MS called ICP-MS. The sample travels 

through the different heating zones and are finally ionized. 

Here, the atomizers used are pyrocoated tubes and tubes with 

centre fixed platforms. In addition, a cobalt hallow cathode lamp 

is used and a wavelength of 242.5nm could be used for assaying. 

Argon serves as a protective gas and serum or urine could be 

introduced into the graphite furnace (GF) directly with 

equivalent volume of modifiers. H 2 O 2 is used to prevent carbon 

residue formation in graphite tube. The electro thermal atomic 

absorption correctly and optimally measures Cobalt (and thus, 

vitamin B12) in serum and urine. It has a detection bound of 0.02 

μg/L Co in serum samples with a relative standard deviation of 

10-18% [34]. 

The main advantages of this method is that it has a high sample 

throughput, it is easy to use, and it has high precision. But the 

main disadvantages involve its less sensitivity, its requirement of 

large sample, and the problems with refraction [34]. Another 

method that is used is the Flame atomic absorption spectrometry. 

The lowest concentration for quantitative recovery is 4 ng/cm 3 of 

vitamin B 12 . The method is used for vitamin B 12 determination in 

pharmaceutical samples. It is used in pharmacology, industry, 

clinical and chemical basic research. [35]. 

3.4. Radioimmunoassay (RIA) 

Radioimmunoassay (RIA) is a highly sensitive laboratory 

technique used to measure minute amount of substrate (such as, 

hormones, antigen and drugs) in the body. RIA is a primer 

immunoassay techniques developed for detecting extremely 

small concentrations [36]. Berson and Yallow developed the first 

radio-isotopic technique to study blood volume and iodine 

metabolism and had used it for the determination of insulin 

levels in human plasma. Later the technique was adapted for 

studying how hormones (especially insulin) are being used in the 

body [35]. This method is so sensitive that it can measure one 

trillionth of grams of substance per milliliter of blood and only 


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small samples are required. These (among other reasons) made 

RIA to quickly become a standard laboratory tool [37]. 

RIA is based on the reaction of antigen and antibody in which 

very small amounts of the radio-labeled antigen competes with 

endogenous antigen for limited binding sites of the specific 

ISSN: 0976-3104 

antibody against the same antigen. The radio-labeled antigen 

have been an analogous in biological activity and/or immunoreactivity 

to the native antigen. For vitamin B12 we use 

Modified intrinsic factor (IF) fractions which have R-proteins 

that bind many porphyrin-ring-containing compounds (i.e., 

cobinamides) by radio assay with [ 57 Co] vitamin B12 [38]. 

Fig: 3. Schematic diagram of an atomic absorption spectrometer. The basic structure of the machine consists of 4 basic structural 

elements; a light source (hollow cathode lamp), an atomizer section for atomizing the sample, a monochromatic for selecting the 

analysis wavelength of the target element, and a detector for converting the light into an electrical signal, amplifier and readout. 

Most commonly used radio-isotope in RIA is 125-I. Other 

emitting isotope such as C14 and H3 have also been used. Some 

other important aspects of RIA are the use of specific antibody 

against particular antigen, and the use of pure antigen as the 

standard or calibrator [37] is attached to tyrosine. These radio 

labeled IFs are then mixed with a known amount of 

cyancoblamine, and they become chemically bound to each 

other. A serum from a patient which contains an unknown 

quantity of IF is added, so the unlabeled (or "cold") IF from the 

serum competes with the radio labeled (or "hot”) IF for 

cyanocoblamine binding sites [39]. 

If the concentration of the “cold" IF increased, more of it binds 

to cyanocoblamine and this will lead to displacement of the 

radio-labeled variant, so the ratio of “cyanocoblamine bound to 

radio labeled antigen” to “free radio labeled IF” is reduced. 

After that, the bound IF is separated from the unbound ones and 

the radioactivity of the free IF that remains in the supernatant are 

measured [39]. The separation of radio-labeled IF bound to 

cyanocoblamine from unbound radio-labeled IF occurs after 

optimal incubation conditions (buffer, pH, time and 

temperatures) [37]. 

Polyethylene glycol joined with double antibody method is 

regularly used to separate bound and free radio-labeled IF. Some 

other techniques in use are the double antigen, charcoal, 

cellulose, chromatography and solid phase technique [37]. 

Calibrations or standard curves are formed from sets of known 

concentrations of the unlabeled standards and from such curves 

the quantity of IF in the unknown samples can be determined. 

Improving the sensitivity of the assay is possible by decreasing 

the amount of radio-labeled analyst and/or antibody, or by 

disequilibrium incubation format in which radio-labeled IF is 

added after initial incubation of IF and cyanocoblamine. This 

technique (just like the others) is supposed to meet the criteria of 

sensitivity, specificity, precision, recovery and linearity and 

dilution [39]. For this technique, the precision has been said to be 

7.9% for 200 ng/L as the concentration of vitamin B12, 6.6 % for 

400 ng/L, and 6.7 % for 800 ng/L. The sensitivity of the assay 

has also been documented as 37 ± 9 ng/L [39]. RIA is well used 

in pharmacology, industry, clinical, and chemical research [38]. 

The principle of radioisotope dilution is based on using unknown 

quantity of non-radioactive vitamin B12 released from serum to 

dilute the specific activity of a known quantity of [ 57 Co] vitamin 

B12. A solution of intrinsic factor concentrate (IFC) with a 

vitamin B12 binding capacity less than the quantity of added 

[ 57 Co] vitamin B12 is used to bind a portion of the mixture of 

radioactive and no radioactive vitamin B12 i.e., to “biopsy” the 

pool of vitamin B12. The vitamin B12 not bound to IFC is 

removed by the addition of coated charcoal [40]. 


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ISSN: 0976-3104 

3.5. High-performance liquid chromatography 

(HPLC) 

It is a liquid chromatography used for non-volatile analyst in 

which the elute do not flow under the force of the gravity but it is 

derived under a hydrostatic pressure of 5000 to 10000 

pounds/square inch through a stainless steel column [41, 42]. 

The HPLC system uses a mobile-phase pump, a reagent pump, 

an auto-sampler, a detector and a data system for data processing 

and system control [43]. 

The system is a chromatography, in which the eluent is filtered 

and pumped through the column, then the sample is loaded and 

injected onto the column and the effluent is monitored using a 

detector, and the peaks are recorded. The pump of the system 

must be able to generate high pressure, performing a pulse-free 

output and deliver flow rates ranging from 0.1 to 10 ml/min [42]. 

In this method, samples are treated very carefully and the 

working pH, heating, agitation, centrifugation and filtration are 

correctly adjusted in accordance with the source of the sample; 

and the resulting solution is injected into the instrument that does 

the measurement. he HPLC must be connected to a suitable 

detector e.g. Micro-mass electrospray mass spectrometer. Its 

results are often precise, and it is very sensitive with detection 

limits of 50 nmol/L [43]. An example of this Instrument is 

Kontron HPLC-system 400. This method is frequently used in 

pharmacology, industry and basic research [43]. 

3.6. Capillary electrophoresis 

Capillary electrophoresis (CE) was first documented in 1981. It 

is used to separate peptides. CE have high resolving power than 

traditional electrophoresis and do not require extremely great 

skills as high-performance liquid chromatography (HPLC) [44]. 

CE is quantitative rather than semi quantitative or qualitative, 

and very small samples (< 10 nL to 1 nL) can be used [43, 44]. 

The schematic structure for CE is composed of sample vial, two 

buffer vials (source & destination), capillary, electrodes, highvoltage 

power supply, detector, and data output. Electroosmotic 

flow forms the main principle in CE [44]. Generally sample for 

CE does not require preparations, but in low concentrations 

biological sample such as serum or plasma, there could be a need 

for pretreatment to prevent ionic strength and protein-rich matrix 

from effecting the migration [44,45]. 

CE can be used for cobalamin separation and for differentiation 

between different forms of the vitamin B12. The procedure of 

cobalamin separation is done by using 70 cm capillary length 

with 20 KV voltage supply, and 9.0 pH tris buffer 25 mM that 

contain 15 mM sodium dodecyl sulfate as electrophoretic buffer 

[46]. 

The main disadvantage of this technique is in its low ability to 

detect the sample (i.e. low sensitivity) due to the wall of the 

capillary, which is dissolved by coupling system of capillary 

electrophoresis-inductively coupled plasma mass spectrometry 

(CE-ICP-MS). It is mainly used in basic research. [46, 47] 

Another source of error that is unique to CE but absent in CE- 

ICP-MS is the electrokinetic sample injection [45]. On the other 

hand, no problems are unique to the coupled system method 

mentioned above. In general controlling the column over 

loading, calibration to prevent sample aging and facilitate 

analysis, and buffering according to the sample pH, are 

important aspects that should always be taken care of while 

separating vitamin B12 [45]. 

[IV] DISCUSSION AND CONCLUDING REMARKS 

The microbiological method remains the routine method for the 

determination of vitamin B12 concentration, despite the fact that 

it is time consuming, and has relatively poor precision, and low 

specificity. This might be because ECL and radioimmunoassay 

which are simpler and faster are very expensive - since they 

require pure intrinsic factor and some special reactants. Also, 

ECL and atomic absorption spectrometry depends on indirect 

measurement of the cobalt. On the other hand, Capillary 

electrophoresis and HPLC methods include the use of UV or 

visible photometry, atomic absorption and ICP-MS. 

Determination of the best way of measuring vitamin B12 

concentration would require critical consideration of the 

required/desired sensitivity and specificity, the available time, 

and the process of preparation of the sample, as well as cost. 

Some of the important characteristics of the different methods 

have been summarized in Table–1. 

Finally, we should say that cases of serious discrepancies 

between results of vitamin B12 concentration determined by 

different methods is highly common. We therefore think that it 

would be important that every laboratory specifies on it reports 

the method that had been used when reporting the results of 

vitamin B12 concentration. This might present clear picture to 

physician and patient. The reasons for deciding to measure 

vitamin B12 concentration should also play a crucial role in 

determining the most appropriate method. For example, the 

investigator might want to use ECL, RIA or atomic absorption 

spectroscopy if the results would be used for clinical/medical 

purposes, while ICP-Ms might be preferred for industrial or 

pharmaceutical needs or for basic research purposes. More 

importantly, several advantages and disadvantages of each of 

these methods govern the choosing of the suitable methods. 

Table–2 has clearly summarized some of these. 


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Table: 1. Comparison of the Sensitivity of different methods used in measuring the concentration of vitamin B12 

Table: 2. Advantages, disadvantages and applications of each of the methods used in measuring the concentration of vitamin 

B12 


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ACKNOWLEDGEMENT 

Special thanks for Dr. Samira Barghouthi the dean of Scientific 

Research at Al-Quds University, who supported and encouraged us all 

the way, and lightened our path with her words and wisdom. 

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ABOUT AUTHORS 

Ola Talal Karmi, has a Bachelor degree in Medical Technology, class 2006, from Al-Quds University, 

East Jerusalem, Palestinian Territories, since 2009 enrolled in the master degree of Hematology 

graduated studies at Al-Quds University- Faculty of Health Professions- Medical Laboratory Science 

Department. Have a cytogenetics training experience. Currently working at the medical diagnostic 

laboratory of Augusta Victoria Hospital- Jerusalem. 

Ashraf Zayed, Master student- Microbiology, Department of Medical Laboratory Sciences, Faculty of 

Health Professions, Al-Quds University. Shared in the 6th Palestinian conference for clinical laboratories, 

2010, Al-Quds University, in a research title “Effect of oral antibiotic on serum vitamin level” as main 

author. Also, shared in 2nd Conference on Biotechnology Research and Application in Palestine, 2010 

An-Najah National University, in a research title “Isolation of putative soil Streptomyces spp showing 

antibacterial activity”. Currently doing a master thesis about Streptomyces spp. 

Suhair F. Baraghithy, has a Bachelor degree in Medical Technology, from Al-Quds University – East 

Jerusalem – Palestinian Territories, since 2009 enrolled in the master degree of Hematology graduated 

studies at Al-Quds University- Faculty of Health Professions- Medical Laboratory Science Department. 3 

years working in clinical laboratories, currently work in Ramallah Governmental hospital. 

Mohammad Alqadi, a master degree student at Microbiology & Immunology program at Al-Quds 

University, East Jerusalem, Palestinian Territories. Received a Bachelor degree in Medical Laboratory 

Science from Arab American University, class 2009, Jenin, Palestine. Currently interested in working at 

Molecular Typing for Bacteria. 

Rasha Emil Ghanem, has a Bachelor degree in Medical Laboratory Sciences from An-Najah National 

University-Nablus- Palestinian Territories. since 2009 enrolled in the master degree of Hematology 

graduated studies at Al-Quds University- Faculty of Health Professions- Medical Laboratory Science 

Department. Currently working at Bethlehem Arab Society- Specialized Surgical Hospital Laboratory. 

Have training programs in Gel Technique for blood banking and Quality Control in Laboratories. 

Participated in several lectures about Thalassemia and Haemophilia. 


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